Extension tubes for balloon catheters

ABSTRACT

A balloon catheter may include a multi-lumen tube having an inflation lumen and a guide wire lumen. The multi-lumen tube may include a proximal end and a distal end and may terminate at a distal tip. The catheter may include an extension tube extending distally from the distal tip of the multi-lumen tube and a dilatation balloon disposed about the multi-lumen tube and the extension tube. The distal tip of the multi-lumen tube may be under the balloon.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority of U.S. ProvisionalApplication No. 60/941,288 filed Jun. 1, 2007, the disclosure of whichis incorporated herein by reference in its entirety as if fully setforth herein.

FIELD OF THE INVENTION

The present disclosure relates to extension tubes for balloon catheters.More particularly, the disclosure is directed to extension tubes forcatheter shafts configured to be used with dilatation balloons to treata relatively long stenosis of blood vessels.

BACKGROUND OF THE INVENTION

Balloon catheter systems for percutaneous angioplasty are well known.The catheter can be introduced to the coronary artery through thefemoral artery. A guide wire is initially positioned within the coronaryartery and a dilation catheter is advanced into the coronary artery overthe guide wire. Near the tip of the distal end of the dilation catheteris a deflated distensible balloon, which can be inflated with fluid. Theinflated balloon can compress a stenosis towards the wall of the vessel.In another example, the catheter can be introduced over a guide wireinto the femoral artery from a percutaneous access site in thecontralateral femoral artery. Subsequent balloon inflation can compressa stenosis towards the wall of the vessel.

In the treatment of longer stenoses, the balloon lengths, and anyassociated lengths, are necessarily increased. During treatment,inflation of the balloon can cause the catheter to undesirably bow orbend, which can result in possible damage to the vessel wall. The bowingor bending of the catheter can result in permanent deformation of apre-mounted stent associated with the catheter. Accordingly, thereremains a need to develop a catheter useful for the treatment of longerarterial vessels.

SUMMARY OF THE INVENTION

In accordance with various aspects of the disclosure, a balloon cathetermay include a multi-lumen tube having an inflation lumen and a guidewire lumen. The multi-lumen tube may include a proximal end and a distalend and may terminate at a distal tip. The catheter may include anextension tube extending distally from the distal tip of the multi-lumentube and a dilatation balloon disposed about the multi-lumen tube andthe extension tube. The distal tip of the multi-lumen tube may be underthe balloon.

According to some aspects of the disclosure, a method for making aballoon catheter may include narrowing a portion of a multi-lumen tubesuch that a distal end of the multi-lumen tube has a diameter smallerthan that of a remainder of the multi-lumen tube, flaring an opening toa guide wire lumen at a distal tip of the multi-lumen tube, inserting anextension tube into the flared opening of the guide wire lumen,connecting a proximal neck of a dilatation balloon to an unnarrowedportion of the multi-lumen tube, and connecting a distal neck of adilatation balloon to the extension tube, such that the distal tip ofthe multi-lumen tube is under the balloon

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the disclosure will be understood from thefollowing description, the appended claims, and the accompanyingdrawings, in which:

FIG. 1 is a side view of an exemplary dilatation balloon catheter inaccordance with various aspects of the disclosure;

FIG. 2 is a cross-sectional view of the catheter along line II-II ofFIG. 1 showing exemplary inflation and guide wire lumens of themulti-lumen tube;

FIG. 3A is a combination plan and cross-sectional side view of thedistal end of an extended length catheter with balloon in accordancewith various aspects of the disclosure;

FIGS. 3B and 3C are cross-sectional views of the catheter along lineIII-III of FIG. 3 illustrating two exemplary configurations of theextension tube; and

FIGS. 4A-4D are side views of the distal end of the catheter of FIG. 1,without the balloon attached, illustrating a method of making theextended length catheter of FIG. 3.

DETAILED DESCRIPTION

One exemplary aspect of the present disclosure provides a ballooncatheter having an extension at its distal end to treat a relativelylong stenosis of arterial vessels.

An exemplary balloon catheter is illustrated in FIG. 1. The catheter 2may comprises a multi-lumen tube 10 having a proximal end 10 a and adistal end 10 b. Referring to the cross-section view of FIG. 2, themulti-lumen tube 10 may include a guide wire lumen 22 and an inflationlumen 20. The guide wire lumen 22 may be sized to receive a guide wire12 such that the guide wire lumen 22 may be moved relative to the guidewire 12 so that the distal end 10 b of the catheter 2 may be directed tothe location of a stenosis of a vessel. Persons skilled in the art mayrefer to catheter 2 as an “over-the-wire” catheter. While the inventionis described using an “over-the-wire” catheter as an example, it isrecognized that the invention is equally applicable to “rapid exchange”catheters as well, where the guidewire lumen extends over only a distalportion of the catheter and is typically 5-50 cm in length.

The catheter 2 may include a manifold 6, for example, a Y-manifold, suchthat the manifold 6 is at the proximal end 10 a of the multi-lumen tube10 during use. The catheter 2 may include a dilatation balloon 8 at thedistal end 10 b of the multi-lumen tube. The inflation lumen 20 mayconvey fluids from a fluid source (not shown) to the dilatation balloon8 in order to inflate the balloon 8.

Dimensions and materials for the guide wire and dilatation catheter areknown in the art and are described, for example, in U.S. Pat. No.4,545,390, the disclosure of which is incorporated herein by reference.

Where a stenosis may be relatively long, longer dilatation balloons maybe necessary. However, as the length of the balloon increases,longitudinal lengthening of the balloon upon radial expansion increasesproportionally. If the catheter is not lengthened in proportion to theballoon lengthening, the distal portion of the catheter can experience acurvature in the shape of a banana/crescent shape or an S-shape, whichcan result, for example, from a twist in the balloon during bonding tothe catheter. This bowing or bending of the catheter can result inpermanent deformation of a pre-mounted stent associated with thecatheter.

FIG. 3A is a side view of the distal end 10 b of the multi-lumen tube10, with the dilatation balloon 8 illustrated in cross-section.Referring now to FIG. 3, the balloon catheter 2 may include an extensiontube 28 extending from the distal end 10 b of the multi-lumen tube 10.The extension tube 28 may provide the catheter 2 with the ability toreduce or even eliminate the aforementioned balloon curvature duringinflation.

The balloon 8 may include distal and proximal necks 54 a, 54 b atopposite ends of the balloon 8 and distal and proximal cone transitionregions 52 a, 52 b between the necks 54 a, 54 b. The extension tube 28may include distal and proximal marker bands 25 a, 25 b that mayindicate the position of the two balloon cone transition regions 52 a(distal) and 52 b (proximal). According to some aspects, the distal andproximal balloon necks 54 a, 54 b may be coupled with the extension tube28 and the multi-lumen tube 10, respectively.

Referring to FIG. 3B, according to an exemplary embodiment, theextension tube 28 may include a guide wire lumen 29 sized to receive theguide wire 12 such that the guide wire lumen 29 may be moved relative tothe guide wire 12 so that the extension tube 28 may be directed to thelocation of a stenosis of a vessel. The guide wire 12 may extend fromthe guide wire lumen 22 of the multi-lumen tube 10 through the guidewire lumen 29 of the extension tube 28 and past the balloon 8. Theinflation lumen 20 may terminate at the distal end 10 b of themulti-lumen 10 and within the length of the dilatation balloon 8. Theinflation lumen 20 may fluidly communicate with an interior volume ofthe dilatation balloon 8 via one or more radial and/or longitudinalopenings.

Referring to FIG. 3C, according to an exemplary embodiment, theextension tube 28 may include a guide wire lumen 129 and an inflationlumen 120. The guide wire lumen 129 may be sized to receive the guidewire 12 such that the guide wire lumen 129 may be moved relative to theguide wire 12 such that the extension tube 28 may be directed to thelocation of a stenosis of a vessel. The guide wire 12 may extend fromthe guide wire lumen 22 of the multi-lumen tube 10 through the guidewire lumen 129 of the extension tube 28 and past the balloon 8. Theinflation lumen 120 may convey fluids from a fluid source (not shown),by way of the inflation lumen 20, to the dilatation balloon 8 in orderto inflate the balloon 8. The inflation lumen 120 and/or the inflationlumen 20 may fluidly communicate with an interior volume of thedilatation balloon 8 via one or more radial and/or longitudinalopenings.

According to some aspects of the disclosure, the multi-lumen tube 10 andthe extension tube 28 may comprise the same materials or differentmaterials. For example, according to various aspects, the tubes 10, 28may comprise various polymers, copolymers, or blends. For example, thematerials may be selected from Pebax®, nylons, etc. In some aspects, theextension tube 28 may comprise at least one nylon material that isdifferent from that of the multi-lumen tube 10. A “different” nylonmaterial can refer to nylons comprising at least one different monomertype. Alternatively, a different nylon material can comprise a copolymeror blend of the same monomer type, but with different respective weightratios of the monomers. Exemplary nylons include, but are not limitedto, homopolymers, copolymers, and blends made from nylon 12, nylon 11,nylon 66, etc. In various aspects, the nylon materials can include othernon-nylon forming monomers, such as, for example, ether formingmonomers. In some aspects, the material may comprise polyether blockpolyamides, such as those available commercially as Pebax®.

According to various aspects of the disclosure, the extension tube 28may be less stiff than the multi-lumen tube 10. That is, the extensiontube 28 may have a lower hardness value so as to minimize the tendencyof the balloon-containing portion of the catheter from forming a bananashape. The hardness of polymeric materials is typically indicated byShore or Durometer hardness. Hardness is determined with a gauge thatmeasures the resistance of the polymer toward deformation, e.g.,indentation or elongation. In one embodiment, the hardness of themulti-lumen and extension tubes 10, 28 are measured with the Shore Dscale.

Although the extension tube 28 may have a reduced hardness value thanthe multi-lumen tube 10, it should not be undesirably flexible.Excessive deformation and/of elongation of the extension tube 28 mayinhibit balloon rewrap due to the excessive deformed length of extensiontube 28. An increased force may be required to pull the poorly rewrappedballoon back into an introducer sheath or a guide catheter.

According to some aspects of the disclosure, the Shore hardness ofextension tube 28, multilumen tube 10, or both can range, for example,from 25D to 95D. In various aspects, the desired hardness of theextension tube 28 and/or multilumen tube 10 can be achieved by blendingnylon materials of different hardness and/or by changing the wallthickness of the extension tube 28 and/or multilumen tube 10,respectively. For example, nylons ranging from 25D to 90D hardness maybe utilized to achieve an intermediary hardness. For example, thehardness of a 65D material can be decreased by blending with a materialof lower hardness. The specific hardness values can be ultimatelydesigned depending on the balloon length.

In accordance with various aspects of the disclosure, the multi-lumentube 10 may have a Shore hardness of at least 60D and the extension tube28 may have a hardness less than that of the multi-lumen tube 10 andbeing no more than 70D, such as a hardness of no more than 69D, 68D,67D, 66D, 65D, 64D, 63D, 62D, 61D, or no more than 60D. In some aspects,the multi-lumen tube 10 may have a Shore hardness of at least 65D andthe extension tube 28 may have a hardness less than that of themulti-lumen tube 10 and being no more than 68D, 67D, 66D, 65D, 64D, 63D,62D, 61D, or no more than 60D. In some aspects, the multi-lumen tube 10may have a Shore hardness of at least 72D and the extension tube 28 mayhave a hardness less than that of the multi-lumen tube 10 and being nomore than 68D, 67D, 66D, 65D, 64D, 63D, 62D, 61D, or no more than 60D.

The extension tube 28 may have a length proportioned to a length of adesired balloon. According to various aspects of the disclosure, balloonlengths may range from 15 mm to 200 mm, such as a length ranging from 15mm to 150 mm, and thus, the corresponding extension tube lengths mayrange from 15 mm to 200 mm±5 mm, such as a length ranging from 15 mm to150 mm±5 mm. According to some aspects, the extension tube length may begreater than the balloon length by an amount ranging from 3-5 mm.

In some aspects of the disclosure, the total length of the catheter 2(including the extension tube 28) can range from 40 cm to 150 cm.

Table 1 provides exemplary lengths for the extension tube 28 based onthe length and diameter of the balloon 8.

TABLE 1 Exemplary Extension tube lengths. Balloon Balloon Extension tubeDiameter (mm) Length (mm) length (mm) 5, 6, 7 15 19.1 9, 10, 12 20 23.58 20 23.7 3, 4, 5, 6, 7 20 24.5 9, 10 30 32.9 3, 4, 5, 6, 7 30 33.7 8 3034.2 9, 10, 12 40 44.3 3, 4, 5, 6, 7 40 44.6 8 40 44.7 9, 10, 12 60 63.28 60 64.0 3, 4, 5, 6, 7 60 64.5 3, 4, 5, 6, 7, 8, 9 80 82.0 3, 4, 5, 6,7 100 102.0 3, 4, 5, 6, 7 120 122.0 3, 4, 5, 6, 7 150 152.0 3, 4, 5, 6,7 200 202.0

The multi-lumen tube 10 in the examples of Table 1 may comprise 90% 72DPebax® and 10% nylon 12, whereas the extension tube 28 may comprise 75%55D Pebax® and 25% 72D Pebax®. Nylon 12 is known to increase thestiffness of the shaft. A cross-section of multi-lumen tube 10 is shownin FIG. 2. The multi-lumen tube 10 may have an overall diameter of 0.05in. and the guide wire lumen 22, being circular, may have a dimension of0.037 in.±0.002 in. The inflation lumen 20 may have a width of 0.037in.±0.002 in. and may be crescent-shaped, having a height of 0.015in±0.002 in. Different guide wire sizes such as, for example, 0.014 in.,0.018 in., or 0.035 in. may be used.

Referring now to FIGS. 4A-4D, an exemplary method of making an extendedlength catheter is illustrated and described. According to variousaspects of the disclosure, the extension tube 28 may be connected withthe multi-lumen tube 10 at the distal end 10 b of the multi-lumen tube10 by, for example, thermally bonding the tubes 10, 28 together.Referring to FIG. 4A, the distal end 10 b of the multi-lumen tube 10 mayinclude a reduced diameter portion 31. The reduced diameter portion 31may be formed, for example, by grinding a portion of the distal end 10 bof the multi-lumen tube 10. In some aspects, as a result of thereduction in diameter at the distal end 10 b, the inflation lumen 20 maybe eliminated from the reduced diameter portion 31. Thus, the reduceddiameter portion 31 may be a mono-lumen tube comprising on the guidewire lumen 22. In some aspects, an inflation lumen 120 may bemaintained, and the reduced diameter portion may be a multi-lumen tube.

The reduced diameter portion 31 has a length extending from a tip 30(the most distal tip of the multi-lumen tube 10) to an interface 33,which abuts the remaining portion 32 of the multi-lumen tube 10. Theremaining portion 32 remains a dual lumen tube having the inflationlumen 20 and the guide wire lumen 22 and, thus, a diameter greater thanthat of the reduced diameter portion 31. According to various aspects ofthe disclosure, the reduced diameter portion 31 may have a length ofabout 2.5 mm, although other lengths can be used depending on theultimate length of the catheter 2 and the extension tube 28. In someaspects, the tip 30 of the reduced diameter portion 31 may be flared toexpand the opening to the guide wire lumen 22 at the distal tip 30 ofthe multi-lumen tube 10. The opening to the guide wire lumen 22 may beflared so that the extension tube 28 can be inserted therein withoutcomprising the diameter of the guide wire lumens 22, 29 with regard toslidably receiving the guide wire 12. The flaring can be accomplishedby, for example, a flaring tool such as, for example, a mandrel.

The extension tube 28 may comprise a mono lumen and may be cut to adesired length, depending on the diameter and length of the balloon 8.The extension tube 28 may include a marker band 25 over a portion of itsouter diameter (but not at the tip of the extension tube 28). The markerband 25 may comprise an annular metal strip, such as, for example, gold,platinum/iridium, or the like, that fits over a catheter. During use ofthe catheter 2, the position of the marker bands may indicate the endsof the balloon portion when dilated.

Referring now to FIG. 4B, an end 27 of the extension tube 28 may beinserted into the flared tip 30 of the reduced diameter portion 31 ofthe multi-lumen tube 10 up to the interface 33 of the remaining portion32 of the multi-lumen tube 10. The insertion can be performed, forexample, with the aid of a mandrel.

As shown in FIG. 4C, the marker band 25 may be moved, for example, bysliding, relative to the extension tube 28 until it contacts the tip 30of the reduced diameter portion 31 of the multi-lumen tube 10. Theoverlap between the extension tube 28 and the multi-lumen tube 10 canrange from 0.075 in. to 0.085 in., although other lengths may beappropriate depending on the overall lengths of the catheter 2 and theextension tube 28. According to various aspects of the disclosure, thejoined lumens 10, 28 can be held in place, for example, via a heatshrink fitting 34. For example, the fitting 34 may be slid over the endof the extension tube 28, the marker band 25, the reduced diameterportion 31 of the multi-lumen tube 10, and a portion of the remainingportion 32 of the multi-lumen tube 10. The heat shrink fitting 34 mayhelp prevent the marker band 25 from shifting.

Referring now to FIG. 4D, the jaws 35 of a heat bonder may be fittedover the end of extension tube 28 (including marker band 25) and thereduced diameter portion 31 such that an end of the jaws 35 aligns withthe interface 33 of reduced diameter portion 31 and the remainingportion 32.

Upon joining the extension tube 28 to the multi-lumen tube 10, theballoon 8 can be mounted on the distal portion of the catheter 2. In oneexample, the balloon 8 may be loaded onto the distal end of the tubewhere the distal end includes the connected extension tube 28. Theballoon 8 may include two necks, one at each extremity of the balloon 8,that snugly fit over the distal portion of the catheter 2. For example,the distal neck of the balloon 8 may fit over the extension tube 28 andthe proximal neck of the balloon 8 may fit over the multi-lumen tube 10.

It should be appreciated that a heat shrink fitting may be placed, forexample, by sliding, over the proximal balloon neck (on the multi-lumentube 10) and adjacent tube area (i.e., the extension tube 10) andpre-shrunk with a hot air jet to hold the proximal balloon neck inplace. Subsequently, the proximal balloon neck may be bonded to thecatheter 2 via, for example, a laser, after which the heat shrinkfitting can be removed. A second heat shrink fitting may be positionedover the distal balloon neck and the bonding process may be repeated tobond the distal balloon neck to the catheter 2.

In operation, the guide wire 12 may first be directed through apatient's vascular system, for example, by a physician. The catheter 2may then be advanced over the guide wire 12 via the guide wire lumen 22.Because of the relatively small diameter of the guide wire 12, there maybe space within the guide wire lumen 22 to administer fluids to thepatient without the need to remove the guide wire 12. The guide wire 12may further include a smaller diameter main wire that tapers at itsdistal end. At the distal end, the main wire may be surrounded by aspring to act as a bumper to minimize injury to the vessel wall.

In some aspects, the guide wire 12 may be placed into a coronary arterythrough the femoral artery and to the site of a stenosis. The distal end10 b of the multi-lumen tube 10 of the catheter 2, including thepreloaded balloon 8, may be directed to the site of the stenosis via theguide wire 12. The stenosis may be treated by inflating the balloon 8with fluid received via the inflation lumen 20 of the multi-lumen tube10. In some aspects, a stent may be preloaded about the balloon 8 suchthat inflation of the balloon expands the stent so that the stent may beimplanted at the site of the stenosis.

According to various aspects of the disclosure, the aforementionedoperation may be used to treat a disease or condition associated with astenosis or thrombosis of vessels relatively longer than a typicalstenosis or thrombosis.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the devices and methods ofthe present disclosure without departing from the scope of theinvention. Other embodiments of the invention will be apparent to thoseskilled in the art from consideration of the specification and practiceof the invention disclosed herein. It is intended that the specificationand examples be considered as exemplary only.

1. A balloon catheter comprising: an independent extension tube; amonolithically formed multi-lumen tube comprising an inflation lumen anda guide wire lumen, the multi-lumen tube having a proximal end segmentand a distal end segment, the extension tube coupled to the distal endsegment of the multi-lumen tube and extending distally therefrom, thedistal end segment of the multi-lumen tube having a flared segmentextending to, and coterminous with, a distal-most end face of themulti-lumen tube, the flared segment configured and dimensioned toreceive the extension tube and direct the extension tube into theguidewire lumen to thereby facilitate positioning and securement of theextension tube to the multi-lumen tube; and a dilatation balloondisposed about the multi-lumen tube and the extension tube therebydefining a balloon-containing portion, the distal end of the multi-lumentube being under the balloon; at least one of the multi-lumen tube andthe extension tube comprising a polyamide material to minimize thetendency of the balloon-containing portion from undesirable bending. 2.The balloon catheter of claim 1, wherein the balloon has a proximal neckand a distal neck at opposed ends thereof, the proximal neck being atthe distal end of the multi-lumen tube and the distal neck being at theextension tube.
 3. The balloon catheter of claim 1, wherein themulti-lumen tube and the extension tube comprise different materials. 4.The balloon catheter of claim 3, wherein the multi-lumen and theextension tube comprise materials having different Shore hardnessvalues.
 5. The balloon catheter of claim 3, wherein at least one of themulti-lumen tube and the extension tube comprises a nylon material. 6.The balloon catheter of claim 5, wherein the multi-lumen and theextension tube comprise materials having different Shore hardnessvalues.
 7. The balloon catheter of claim 1, wherein the length of theextension tube ranges from 15 mm to 200 mm & 5 mm.
 8. The ballooncatheter of claim 1, wherein the length of the extension tube rangesfrom 15 mm to 150 mm & 5 mm.
 9. The balloon catheter of claim 1, whereinthe length of the extension tube is greater than the length of theballoon by an amount ranging from 3-5 mm.
 10. The balloon catheter ofclaim 1, wherein the extension tube comprises a monolumen tubeconfigured to receive a guide wire.
 11. The balloon catheter of claim 1,wherein the extension tube is insertably received by the guide wirelumen of the multi-lumen tube.
 12. The balloon catheter of claim 1,wherein the multi-lumen tube has a first outer diameter proximally ofthe distal end of the multi-lumen tube, the distal end of themulti-lumen tube having a second outer diameter smaller than the firstouter diameter.
 13. The balloon catheter of claim 12, wherein theinflation lumen and the guide wire lumen are defined completely throughthe distal-most end of the multi-lumen tube.
 14. The balloon catheter ofclaim 1, wherein the extension tube is insertably received by anenlarged opening defined in a distal end of the guide wire lumen of thedistal end of the multi-lumen tube.
 15. The balloon catheter of claim 1,wherein the inflation lumen and the guide wire lumen are arranged sideby side.
 16. A balloon catheter comprising: an independent extensiontube; a monolithically formed multi-lumen tube comprising an inflationlumen and a guide wire lumen, the multi-lumen tube having a proximal endand a distal end, each of the inflation lumen and the guide wire lumenof the multi-lumen tube having a coterminous distal end, the guide wirelumen defining an enlarged distal opening, the extension tube secured tothe distal end of the multi-lumen tube and extending distally therefrom,the enlarged distal opening of the guidewire lumen facilitating mountingof the extension tube to the distal end of the multi-lumen tube, themulti-lumen tube having a greater Shore hardness than that of theextension tube; and a dilatation balloon disposed about the multi-lumentube and the extension tube to define a balloon-containing portion,wherein the Shore hardness of the multi-lumen tube and the extensiontube are selected to minimize the tendency of the balloon-containingportion from undesirable bending, the distal end of the multi-lumen tubebeing under the balloon.
 17. The balloon catheter of claim 16, whereinthe multi-lumen tube has a Shore hardness of at least 60D and theextension tube has a hardness less than that of the multi-lumen andbeing no more than 70D.
 18. The balloon catheter of claim 16, whereinthe multi-lumen tube has a Shore hardness of at least 65D and theextension tube has a hardness less than that of the multi-lumen andbeing no more than 65D.
 19. The balloon catheter of claim 16, wherein atleast one of the multi-lumen tube and the extension tube comprises apolyether block polyamide.
 20. The balloon catheter of claim 16, whereinthe multi-lumen tube has a first outer diameter proximally of the distalend of the multi-lumen tube, and wherein the distal end of themulti-lumen tube has a second outer diameter smaller than the firstouter diameter.
 21. A balloon catheter comprising, an independentextension tube comprising a guide wire lumen and an inflation lumen; amonolithically formed multi-lumen tube comprising an inflation lumen anda guide wire lumen, the multi-lumen tube having a proximal end and adistal end, the extension tube coupled to the distal end of themulti-lumen tube and extending distally therefrom, the distal end of themulti-lumen tube flaring to a distal-most end of the multi-lumen tube tofacilitate securement of the extension tube to the guide wire lumen ofthe multi-lumen tube without compromising a diameter of the guide wirelumen; and a dilatation balloon disposed about the multi-lumen tube andthe extension tube to define a balloon-containing portion, the distalend of the multi-lumen tube being under the balloon, at least one of themulti-lumen tube and the extension tube comprising a polyamide materialwherein the multi-lumen tube has a greater Shore hardness than that ofthe extension tube to minimize the tendency of the balloon-containingportion from undesirable bending.
 22. A catheter comprising, a cathetertube defining a longitudinal axis and having a proximal end and a distalend, the catheter tube defining an inflation lumen and a guide wirelumen, the guidewire lumen flaring to a distal-most end of the cathetertube to define an enlarged opening adjacent the distal-most end of thecatheter tube, the enlarged opening defining an internal dimensiongreater than a corresponding internal dimension proximal of the distalend, an extension tube mounted with respect to the catheter tube, theextension tube being independent of the catheter tube, and being atleast partially positioned within the enlarged opening of the guide wirelumen, to permit reception and passage of a guide wire; and a balloonmember having a proximal balloon end mounted to the catheter tube and adistal balloon end mounted to the extension tube, and defining aninterior expandable chamber in fluid communication with the inflationlumen, the balloon member adapted to transition between unexpanded andexpanded conditions thereof.